Diabetes and periodontal therapy

Abstract

This issue of The Journal of the American Dental Association (JADA) contains a report1Michalowicz BS Hyman L Hou W et al.Factors associated with the clinical response to nonsurgical periodontal therapy in people with type 2 diabetes mellitus.JADA. 2014; 145: 1227-1239PubMed Google Scholar of the periodontal treatment response among people who participated in the Diabetes and Periodontal Therapy Trial (DPTT).2Engebretson SP Hyman LG Michalowicz BS et al.The effect of nonsurgical periodontal therapy on hemoglobin A1c levels in persons with type 2 diabetes and chronic periodontitis: a randomized clinical trial.JAMA. 2013; 310: 2523-2532Crossref PubMed Scopus (178) Google Scholar The DPTT is a large, multicenter randomized controlled clinical trial that was designed to study the effect of nonsurgical periodontal therapy among people who have type 2 diabetes mellitus and periodontitis. The periodontal treatment consisted of two or more sessions of scaling and root planing (totaling more than 2.5 hours and involving the use of local anesthetic) and follow-up supportive periodontal care. The main conclusion of this six-month trial was that nonsurgical periodontal therapy did not improve glycemic control in patients with type 2 diabetes who had periodontitis.2Engebretson SP Hyman LG Michalowicz BS et al.The effect of nonsurgical periodontal therapy on hemoglobin A1c levels in persons with type 2 diabetes and chronic periodontitis: a randomized clinical trial.JAMA. 2013; 310: 2523-2532Crossref PubMed Scopus (178) Google Scholar This trial has received considerable attention because its findings are contrary to what many people anticipated—and because it did not support results of smaller clinical trials and meta-analyses that showed improvements in hemoglobin A1c (HbA1c) levels as a result of nonsurgical periodontal therapy.3Borgnakke WS Chapple IL Genco RJ et al.The multi-center randomized controlled trial (RCT) published by the Journal of the American Medical Association (JAMA) on the effect of periodontal therapy on glycated hemoglobin (HbA1c) has fundamental problems.J Evid Based Dent Pract. 2014; 14: 127-132Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar We wish to address the generalizability of the DPTT. As reported by the authors in this issue of JADA,1Michalowicz BS Hyman L Hou W et al.Factors associated with the clinical response to nonsurgical periodontal therapy in people with type 2 diabetes mellitus.JADA. 2014; 145: 1227-1239PubMed Google Scholar the patient sample of the DPTT reflects the population of people with diabetes in the United States. The DPTT included participants who had type 2 diabetes with HbA1c levels between 7 percent and less than 9 percent; 72 percent of the participants were obese (body mass index [BMI] greater than 30 kilograms per square meter).1Michalowicz BS Hyman L Hou W et al.Factors associated with the clinical response to nonsurgical periodontal therapy in people with type 2 diabetes mellitus.JADA. 2014; 145: 1227-1239PubMed Google Scholar The National Health and Nutrition Examination Survey is a population-based survey of people with diabetes in the United States; its results demonstrated that only 12.6 percent of people with diabetes in the United States are estimated to have HbA1c levels greater than 9 percent and 62.4 percent to have a BMI of 30 or greater.4Ali MK Bullard KM Saaddine JB Cowie CC Imperatore G Gregg EW Achievement of goals in U.S. diabetes care, 1999-2010.N Engl J Med. 2013; 368: 1613-1624Crossref PubMed Scopus (735) Google Scholar, 5Kramer H Cao G Dugas L Luke A Cooper R Durazo-Arvizu R Increasing BMI and waist circumference and prevalence of obesity among adults with type 2 diabetes: the National Health and Nutrition Examination Surveys.J Diabetes Complications. 2010; 24: 368-374Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar The DPTT does not address the possible effect of periodontal treatment in the 12 percent of the population with HbA1c levels greater than 9 percent or the 50 percent of the population with HbA1c levels less than 7 percent, because efforts were made to exclude these patients. However, the magnitude of obesity was not constrained by trial entry criteria. Patients with type 2 diabetes who have HbA1c levels higher than 9 percent and a BMI of less than 30 are rare. Because the participant sample was typical of patients with diabetes both in terms of HbA1c and obesity, the results of the DPTT should be viewed as fully generalizable to patients with diabetes in the United States. In the article by Michalowicz and colleagues1Michalowicz BS Hyman L Hou W et al.Factors associated with the clinical response to nonsurgical periodontal therapy in people with type 2 diabetes mellitus.JADA. 2014; 145: 1227-1239PubMed Google Scholar in this issue of JADA, the magnitude of periodontal treatment response in the DPTT is reported and compared with that in other studies. Data from recent large clinical trials of periodontal therapy6Michalowicz BS Hodges JS DiAngelis AJ OPT Study et al.Treatment of periodontal disease and the risk of preterm birth.N Engl J Med. 2006; 355: 1885-1894Crossref PubMed Scopus (411) Google Scholar, 7Offenbacher S Beck JD Jared HL Maternal Oral Therapy to Reduce Obstetric Risk (MOTOR) Investigators et al.Effects of periodontal therapy on rate of preterm delivery: a randomized controlled trial.Obstet Gynecol. 2009; 114: 551-559Crossref PubMed Scopus (180) Google Scholar have shown that there are variations in the effect of periodontal therapy on measures of periodontal disease among various trial sites, and that the treatment effect may be less than the treatment response reported in small-scale, single-center trials. It is likely that periodontal treatment effects reported in large, multicenter trials provide a realistic and generalizable estimate of the magnitude of treatment response that is achieved in the everyday practice of dentistry. A major advantage of large multicenter trials is that their findings are more generalizable to the real world of patient care than are those of small trials that often are conducted by specialists in highly selected patient samples. In diabetes, it is not uncommon that the conventional wisdom based on epidemiologic findings or on results of single-center studies does not hold up in multicenter trials. Epidemiology is useful for generating hypotheses regarding the effects of particular treatments, but the effects as compared with no treatment or an alternative treatment can be measured only in a trial. Single-center studies often are not generalizable because of the particulars of the technique or the dynamics of the team or because the characteristics of the patients cannot be generalized. The investigators in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial examined the epidemiologic hypothesis that aiming for normal levels of glucose would reduce cardiovascular events.8ACCORD Study Group; Gerstein HC Miller ME Genuth S et al.Long-term effects of intensive glucose lowering on cardiovascular outcomes.N Engl J Med. 2011; 364: 818-828Crossref PubMed Scopus (845) Google Scholar The Normoglycemia in Intensive Care Evaluation–Survival Using Glucose Algorithm Regulation (NICE-SUGAR) study was a multicenter trial9NICE-SUGAR Study Investigators; Finfer S Liu B Chittock DR et al.Hypoglycemia and risk of death in critically ill patients.N Engl J Med. 2012; 367: 1108-1118Crossref PubMed Scopus (689) Google Scholar designed to examine the benefit of rigorous management of blood sugar levels in an intensive care unit, the results of which had been demonstrated previously in a single-center study. The results of both studies demonstrated no benefit, but rather harm in the form of excess mortality. The results of both trials were embraced by the community of general medical practitioners because, frankly, they made both patients’ and practitioners’ lives easier because they did not have to worry about another expensive and burdensome treatment. However, the same results were vilified by subspecialists who insisted that the intervention could be performed more skillfully or that there are subpopulations who would benefit from it. Subsequent guidelines10American Diabetes Association Standards of medical care in diabetes: 2014.Diabetes Care. 2014; 37: S14-S80Crossref PubMed Scopus (3695) Google Scholar continue to support the unpopular conclusions of the ACCORD and NICE-SUGAR studies. For now, it is well accepted that these approaches to diabetes management that were widely touted on the basis of findings from epidemiologic studies and single-center studies were not only unhelpful but also potentially harmful in the general population. DPTT has been characterized as having fundamental problems, and there has been a call by prominent periodontal researchers for “all interested parties to refrain from using these [DPTT] study results as a basis for future scientific texts, new research projects, guidelines, policies, and advice regarding the incorporation of necessary periodontal treatment in diabetes management”3Borgnakke WS Chapple IL Genco RJ et al.The multi-center randomized controlled trial (RCT) published by the Journal of the American Medical Association (JAMA) on the effect of periodontal therapy on glycated hemoglobin (HbA1c) has fundamental problems.J Evid Based Dent Pract. 2014; 14: 127-132Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar (italics added for emphasis). Concerns that have been expressed about the DPTT include the following: an effect of periodontal treatment on glycemic control would not be expected as a result of periodontal therapy because the participants’ baseline HbA1c levels already were close to those reflecting good glycemic control3Borgnakke WS Chapple IL Genco RJ et al.The multi-center randomized controlled trial (RCT) published by the Journal of the American Medical Association (JAMA) on the effect of periodontal therapy on glycated hemoglobin (HbA1c) has fundamental problems.J Evid Based Dent Pract. 2014; 14: 127-132Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar, 11Chapple IL Borgnakke WS Genco RJ Hemoglobin A1c levels among patients with diabetes receiving nonsurgical periodontal treatment (comment).JAMA. 2014; 311: 1919-1920Crossref PubMed Scopus (12) Google Scholar;the periodontal treatment was inadequate3Borgnakke WS Chapple IL Genco RJ et al.The multi-center randomized controlled trial (RCT) published by the Journal of the American Medical Association (JAMA) on the effect of periodontal therapy on glycated hemoglobin (HbA1c) has fundamental problems.J Evid Based Dent Pract. 2014; 14: 127-132Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar, 11Chapple IL Borgnakke WS Genco RJ Hemoglobin A1c levels among patients with diabetes receiving nonsurgical periodontal treatment (comment).JAMA. 2014; 311: 1919-1920Crossref PubMed Scopus (12) Google Scholar;pronounced obesity would mask any decreased inflammatory response caused by successful periodontal treatment3Borgnakke WS Chapple IL Genco RJ et al.The multi-center randomized controlled trial (RCT) published by the Journal of the American Medical Association (JAMA) on the effect of periodontal therapy on glycated hemoglobin (HbA1c) has fundamental problems.J Evid Based Dent Pract. 2014; 14: 127-132Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar, 12Merchant AT Hemoglobin A1c levels among patients with diabetes receiving nonsurgical periodontal treatment (comment).JAMA. 2014; 311: 1919Crossref PubMed Scopus (5) Google Scholar;antimicrobial agents and other treatment strategies were not used as part of the periodontal therapy.13Vergnes JN Hemoglobin A1c levels among patients with diabetes receiving nonsurgical periodontal treatment (comment).JAMA. 2014; 311: 1920-1921Crossref PubMed Scopus (6) Google Scholar These concerns were addressed by the DPTT investigators in The Journal of the American Medical Association (JAMA).14Engebretson SP Hyman LG Michalowicz BS Hemoglobin A1c levels among patients with diabetes receiving nonsurgical periodontal treatment: reply.JAMA. 2014; 311: 1921-1922Crossref PubMed Scopus (5) Google Scholar Rather than urge censorship of the DPTT's results, we encourage interested parties to carefully read the comments about the DPTT and the investigators’ reply in JAMA and to make their own decisions about the study's findings. Overall, it is clear to us that the DPTT was designed and conducted so that its results are generalizable and applicable to most patients with type 2 diabetes who are seen in typical dental and medical practices in the United States. No clinical trial can answer all questions about a given treatment or disease—and the DPTT is no exception. It did not answer all questions regarding the possible effectiveness of periodontal treatment on glycemic control among all patients with type 2 diabetes. However, it provides important information about the lack of effectiveness of nonsurgical periodontal treatment in reducing hyperglycemia in most patients with type 2 diabetes. To urge censorship of the results of a well-designed and executed clinical trial is contrary to the values of academic research and its foundation of ethical open inquiry, transparency, publication and dissemination of knowledge that must be considered by those who make health care decisions. The trial serves as a valuable resource for dentists and physicians who treat patients with type 2 diabetes and provides important information for researchers in planning future studies. When conventional wisdom in diabetes care is challenged by high-quality randomized controlled trials such as ACCORD, NICE-SUGAR and DPTT, it is imperative that we pay attention to the results. Although well-conducted trials with unpopular results, such as ACCORD, NICE-SUGAR and DPTT, often generate criticism, large multicenter trials that are generalizable are the standard for evidence-based care. New treatments may one day reveal opportunities for lowering patients’ HbA1c levels below 6 percent, rigorous management of patient glucose levels in intensive care units, and periodontal care for those who have periodontitis. Although the DPTT findings did not show any effect on lowering hyperglycemia in patients with type 2 diabetes, they did show that periodontal treatment was safe and effective in reducing signs of periodontal disease in these patients. Until further evidence or new treatment methods are available, nonsurgical periodontal care should be delivered to achieve the important benefit of improved oral health, and not for the purpose of improving glycemic control in the vast majority of patients with type 2 diabetes. ▪